1. Field of the Invention
The present invention relates to physical therapy devices and more particularly to a rehabilitative apparatus for treatment of reflex sympathetic dystrophy and related disorders that cause weakness of muscles, joint stiffness, loss of mobility, pain and in severe cases, an atrophy of the associated tissue. Even more particularly, preferred embodiments of the present invention relate to improved apparatus for the treatment and rehabilitation of the effects of reflex sympathetic dystrophy involving the fingers, hands and limbs, including the joints of the wrists, elbows, ankles, knees, hips and shoulders. For those embodiments of the invention involving the hands, wrists and fingers, a pair of hand grips are attach to elongated shafts and, the distal ends of the shafts are attached through a gear system to a flywheel or equivalent inertial device. The gear and flywheel system allows for clockwise and counterclockwise rotations of the flywheel by rotation of the grips, involving a coordinated involvement of both hands and forearms. The patient puts the system in motion by rotating the handles in successive clockwise and counterclockwise directions. The afflicted portion of the limb uses, what residual strength is available. The inertia that has been input to the flywheel augments the movement of the limb past the afflicted limit, thereby extending the range of motion and functionality.
2. General Background of the Invention
Reflex sympathetic dystrophy (RSD) is a painfull condition usually arising from trauma involving nerves. In a typical example, a simple fracture of the wrist may hurt beyond what would normally be expected despite proper casting of the limb. In a few days the pain intensifies and assumes a constant burning quality, usually involving the whole limb. The skin may become sensitive to the point that light touch or even air from such as a fan causes excruciating pain. Distrophic changes ensue, initially with swelling, changes in color, temperature and appearance of the skin, followed by progressive atrophy of muscles, shortening of ligaments, ankylosing (or freezing) of the joints and later regional osteoporosis (or thinning) of the bone. The end result may be an inability to filly open or close the hand, limited rotation of the wrist for pronation/supination and flexion/extension. The ankle, elbow, knee and especially the shoulder joint may be similarly affected if related tissues are injured.
The current treatments universally include medications, nerve blocks and other similar modalities, but physical therapy is always necessary. Current physical therapy employs passive exercises such as having a therapist mobilize the affected limb. However, this therapy is limited by the patient's pain and fear of being hurt due to excessive manipulation by the therapist. Machines for continuous passive motion (CPM) were developed for stiff or surgically repaired joints but do not take into account the patient's intense pain and tissue sensitivity. We have determined that active exercises, by involving the brain, spinal cord, nerves and nerve-muscle junction are a more complete approach, and are necessary for the reeducation of the limb and reversal of the distrophic changes, not achieved through purely passive exercises.
In treating patients with RSD, we have found many have many developed "overuse syndromes" of the limb, mainly involving tendinitis from excessive exercises. It has become clear that the available exercise machines do not take into account the fact that these patients have to work not only against the machine's resistance, but also the internal resistance caused by the shortened muscles and ligaments as well as the stiffened and frozen joints.
We have developed a machine to address the specific needs of patients with RSD, although other medical conditions may benefit through use of the inventive apparatus. It is likely that treatment of the dystrophy from strokes, collagen diseases such as rheumatoid arthritis and similar injuries and abnormalities may be similarly effective as in RSD. The same principles used to treat the wrist as in the machine herein described, may be utilized to treat other areas of the body affected by RSD, such as the fingers, elbow, shoulder, ankle and the knee.
The inventive apparatus utilizes energy stored in an inertial device, such as a flywheel, to aid a patient's active exercises. Those skilled in the art will appreciate that other inertial devices including those electrically activated (as servo or stepping motors) may provide the inertial energy for the therapy. The machine's resistance is maximal initially, due to the flywheel's inherent inertia and it decreases rapidly with the resistance becoming negative at the end of the cycle (i.e., tending to continue the action). This allows the patient to start the exercise when the afflicted limb strength is maximal and joint stiffness and restriction are minimal. As the motion progresses, the internal resistance of the tissues increase and the patient's ability to accelerate the flywheel decreases. At that point the flywheel momentum carries the motion of the limb further, effectively providing a passive stretching of the tissues. By way of example, a patient who lacks forty-five degrees of mobility to fully supinate the hand (palm up) may start the motion of the apparatus with the hand fully pronated (palm down). By starting the action of the inventive apparatus with available joint strength, the apparatus may input the absorbed internal inertia back to the joint to carry it through to the weakened position, i.e., to reach the supinated position. The flywheel inertia will maintain the wrist rotation for a few more degrees until the internal resistance of the dystrophy affected tissues makes the wheel stop. The movement is therefore, active at the first portion of the cycle and passive at the end, preventing the inevitable overuse of muscles and ligaments in an active attempt to achieve a few more degrees of motion.
The inventive apparatus preferably is adapted for simultaneous bilateral operation, with concomitant pronation or supination of both limbs. This allows for a better retraining of the affected limb/joint, proprioception and coordination deficits benefitting from the communication between the right and left sides of the brain, restoring neural pathways compromised by the RSD. The use of the normal limb during the exercise may allow the central nervous system to use simultaneous bilateral use as a template to correct the incoordination of the malfunctioning limb/joint. The bilateral handles also allow the patient more strength to initiate the motion and more braking power to stop the rotation (oppose the inertia), effectively increasing the safety and making the apparatus more user friendly.
Pain is a significant deterrent to a patient's ability to exercise. Proper positioning of the limb/joint is a must. The inclusion of conical handles in the preferred embodiment allows for a more physiologic grasp, respecting the anatomy of a partially closed hand. In the preferred embodiment, the conical handles are attached to a gimbaled structure in order to permit the physiologic radial/ulnar deviation that occurs during pronation/supination.
Various patents have been issued for apparatus directed to physical therapy. None that we are aware of are directed to the special problems presented in the rehabilitation of a patient suffering from RSD. There are a variety of exercise machines, some including rehabilitation for occupational objectives. Early examples include the Hopkins U.S. Pat. No. 4,070,071 and the Bell U.S. Pat. No. 1,899,255. An apparatus directed specifically to mobilizing stiff joints is disclosed is U.S. Pat. No. 2,387,966 issued to Zander.
The Newman U.S. Pat. No. 4,077,626 provides an exercising apparatus that includes a platform, a bench mounted on the platform and adapted to provide a foot space on each side of the bench a bar traversing the bench attached at its ends to a pair of lines, a linear-to-rotational motion converter operably attached to said lines and adapted to convert the linear extension of said lines to rotational motion and to rewind said lines when said extension is relaxed, and a flywheel responsive to said linear-to-rotational motion converter and adapted so the pulling of said lines results in the rotation of said flywheel.
U.S. Pat. No. 4,337,050 issued to Engalitcheff provides a method and apparatus for rehabilitation of damaged limbs for use in operation of a tool, wherein accessories with handles corresponding to the handles of familiar tools are attached to a shaft in a manner such that the movements of the handle correspond to the normal operation of the tool product rotation of a shaft. A preselected resistance is applied to the rotation of the shaft by electrical, pneumatic, hydraulic, or mechanical means, and the resistance and the accessory attached can be varied in accordance with the capability of the damaged limb.
U.S. Pat. No. 4,647,036 issued to Huszczuk discloses a device for enabling the testing of a person's physical condition, by enabling measurement of the energy expended by the person to be tested thereby, in manually maintaining rotation of a flywheel in a stationary bicycle, against resistance applied to the flywheel, for use in determining the efficiency of the person's body in using energy, as an indication of such person's physical condition.
U.S. Pat. No. 4,809,970 issued to Beistegui provides and inertia mechanism for gymnastic bicycles having a pedaling axle. The mechanism includes an inertia flywheel and a set of cogged crowns of different diameters and different number of cogs mounted on the flywheel and operatively connected to each other and to the pedaling axle so that weight and the size reduction of the flywheel are counterbalanced by the set of the cogged crowns actuated upon the actuation of the pedaling axle.
Prior active exercise machines can induce overuse damage. There are several assisted passive devices used for rehabilitation such as a continuous positive motion or "CPM" devices, but they do not allow for the patient's control. They do not stimulate muscle use or proprioception.